Therapeutic implications of hepatitis B virus genotypes

Authors

  • Chun-Jen Liu,

    1. Department of Internal Medicine, Division of Gastroenterology,
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  • Jia-Horng Kao,

    1. Department of Internal Medicine, Division of Gastroenterology,
    2. Graduate Institute of Clinical Medicine,
    3. Hepatitis Research Center
    4. Department of Medical Research, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
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  • Ding-Shinn Chen

    1. Department of Internal Medicine, Division of Gastroenterology,
    2. Graduate Institute of Clinical Medicine,
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Prof. Jia-Horng Kao, Hepatitis Research Center, National Taiwan University Hospital, 1 Chang-Te St., Taipei 100, Taiwan
Tel: +886-2-23123456 ext 7307
Fax: +886-2-23825962
e-mail: kjh@ha.mc.ntu.edu.tw

Abstract

Abstract: Background/Aims: Hepatitis B virus (HBV) is a global health problem. In addition to the implementation of universal hepatitis B vaccination, effective and individualized treatment of chronic hepatitis B to prevent progression into end-stage liver diseases and hepatocellular carcinoma is still needed. HBV has been designated eight genotypes (A–H) based on genome sequence divergence. The epidemiology of HBV genotypes and their implications on the responses to antiviral therapy have become increasingly recognized in both Asian and Western countries.

Methods: Published data are thus reviewed.

Results: Each genotype has its distinct geographical and ethnic distribution. Genotypes A and D occur frequently in Africa, Europe, and India, while genotypes B and C are prevalent in Asia. Genotype E is restricted to West Africa, and genotype F is found in Central and South America. The distribution of genotypes G and H is less clear. Accumulating evidence indicates a better sustained response to conventional interferon in patients with genotype B than those with C, and in patients with genotype A than those with D. In contrast, conflicting results exist regarding the response to pegylated interferon. On the other hand, the therapeutic responses to nucleoside/nucleotide analogues are comparable among patients with different HBV genotypes. The impact of HBV subgenotypes, mixed genotype infections, and recombinants of different genotypes on the response to antiviral treatments awaits further examinations.

Conclusion: Remarkable clinical and pathogenic differences do exist among HBV genotypes; however, researches on molecular and virologic mechanisms underlying the clinical phenotypes of different HBV genotypes are urgently needed.

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